2-alkylidene oxetane compounds

ABSTRACT

Polymerizable unsaturated oxetane compounds having the structure: WHEREIN R1, R2, R3 and R4 are selected from the group consisting of methyl or ethyl have been discovered. They may be prepared in high yield by reacting a suitable base, preferably potassium tbutoxide with a substituted 3-oxobutylene or 3-oxopentylene compound such as, for example, 2,2,4-trialkyl-3-oxopentyl tosylate or 2,2,4-trialkyl-3-oxopentyl isobutyrate in an inert organic solvent, preferably benzene. Polymers and copolymers are prepared from the oxetane compounds.

United States Patent Robinson, III et al.

[l5] 3,692,801 [45] Sept. 19, 1972 [541 Z-ALKYLIDENE OXETANE COMPOUNDS[72] Inventors: Alfred G. Robinson, III, 501 W.

Terrace Dr.; Anthony W. McCollum, 404 Hillmont, both of Longview, Tex.75601 [22] Filed: Sept. 16, 1970 21 Appl. No.: 72,839

[52] US. Cl. ..260/333, 260/80.3 R, 260/88.3 A, 260/88.l R, 260/488 F,260/488 1, 260/594,

260/456 P [51] Int. Cl. ..C07d 3/00 [58] Field of Search ..260/333 [56]References Cited OTHER PUBLICATIONS Chemical Abstracts, Subject Index,Vol. 68 (1968) p. 2676s Robert et al., Basic Principles of OrganicChemistry (1964), p. 475.

Weissberger, A., Heterocyclic Compounds with Three and Four-MemberedRings, Part Two, (1964) pp.

Primary Examiner-Norma S. Milestone Attomey-Cecil D. Quillen, Jr. andDaniel B. Reece, III

[57] ABSTRACT Polymerizable unsaturated oxetane compounds having thestructure:

11 Claims, No Drawings Z-ALKYLIDENE OXETANE COMPOUNDS This inventionrelates to novel unsaturated oxetanes and to a novel method for theirpreparation. More particularly, the invention is directed to2-alkylidene oxetane compounds and to their preparation. ln anotheraspect, the invention relates to the preparation of polymers of2-alkylidene oxetane compounds.

, The compounds of the invention may be represented by the followingstructure:

\ \CH, \o/

More recently, Crandall and Meyer have reported the synthesis of1-methyl-3-methylene-2-oxabicyclo[2.2.01 hexane by photolysis of5,6-heptadien-2-one;

The starting tosylate material may be prepared by any of the procedureswell known'to the art as, for instance, by reacting 2 moles of themonoisobutyrate ester of 2,2,4-trialkyl-l,3-pentanediol to produceisopropyl-l l -dialkyl-2-hydroxyketone and reacting this ketone withp-toluenesulfonyl chloride. This synthesis can be represented by thefollowing sequence of reactions:

wherein R, R R and R are defined hereinabove.

An alternate method for the preparation of the novel compounds of theinvention comprises reacting 2,2,4- tri-lower alkyl-3-oxo-l-pentanolisobutyrate with a suitable base. The method will be illustrated in oneof the working examples below.

Suitable bases with which the tosylate compound may be reacted includesodium methoxide, potassium tert-butoxide and sodium hydride. Not all ofthe alkali metal alkoxide class of bases provide the desired product orfor that matter react at all. For instance, lithium methoxide and sodiumhydroxide fail to react. The reaction is preferably effected by heatingstoichiometric equivalents of the reactants to reaction temperature,ordinarily at least about 50C. usually up to C. Although the reactioncan be carried out in the absence of a liquid reaction medium, it isadvantageously carried out in the presence of an organic solvent. Theuse of a solvent facilitates contact between the reactants and aids intemperature control. The solvent should be inert, that is, should notreact with the reactants or the product. Suitable solvents include, forexample, alcohols such as methanol; aromatic hydrocarbons such asbenzene, toluene, xylenes, ethylbenzene, dimethylformamide,dimethylacet'amide,

SOaK

wherein R, R R and R are as defined hereinabove.

w AEH:

dimethylsulfoxide, etc. The preferred solvent is benzene and thepreferred base potassium t-butoxide.

In-nna The novel compounds of the invention may be recovered from thereaction mixture by acidifying the mixture and pouring the acidifiedlayer in water to form an aqueous layer and an organic layer. Anysuitable acid may be used in this step. The aqueous layer is thenextracted with chloroform and the organic layer washed, dried, filteredand distilled to obtain the desired oxetane product.

The unsaturated oxetane compounds may be homopolymerized orinterpolymerized with at least one copolymerizable, ethylenicallyunsaturated monomer. Among the monomers with which the unsaturatedcompounds of the invention may be copolymerized are, for example,ethylenicaliy unsaturated components such as ethylene, propylene,butene-l, butadiene, styrene, vinyl toluene, monoand substitutedstyrenes such as monochlorostyrene, vinyl esters, acetylene, vinylethers, vinyl halides, vinylidene halides, acrylic and methacrylic acidand its derivatives, e.g., amides, esters, nitriles and the like. Onesuch preferred copolymer is the copolymer prepared using styrene.

Polymerization of the oxetane compounds of the invention by themselvesor with one or comonomers can be carried out using polymerizationprocesses known in the art such as anionic, cationic, coordination andfree radical processes. Typical catalyst for cationic polymerization areFriedel-Crafts catalysts such as AlCl AlBr TiCl BF SnCl P S0 SbCl FeCl,ZnBr, Zncl and the strong Lewis acids such as trifluoro acetic acid.Examples of coordination catalysts which can be used include triethylaluminum and titanium trialuminum. A co-catalyst may be required toinitiate the polymerization. Any of the co-catalysts commonly employedin cationic polymerizations to supply l-l may be employed for thispurpose. Polymerization of the oxetanes of the invention is quite anexothermic reaction and extensive cooling is needed to avoid excessivetemperatures. The polymerization temperature may vary widely dependingupon the monomer or monomers selected for the polymerization butordinarily falls in the range of about 70 to l00C. Unless caution isexerted, temperatures much above 100 C. have a tendency to rupture theoxetane moiety and therefore are usually avoided when it is desired topreserve the oxetane moiety as part of the polymeric chain.

Thus, the polymerization of the novel compounds to form homopolymers andcopolymers produces novel polymers having as a recurring oxetane unit:

wherein R, R R and R are as defined hereinabove and n is a numberbetween 2 and 1,000, preferably 100 to 500.

An example of copolymers that may be prepared from the oxetane compoundsof the invention are:

more

cent oxetane units. One such particular copolymer is the copolymersprepared from styrene and 2-alkylidene oxetane which can be representedas follows:

wherein R, R R", R and n are as defined hereinabove.

If desirable a chain terminator can be used such as, for example,hydrogen, to control the molecular weight of the oxetane copolymers.Also, pigments, stabilizers, anti-slip agents, anti-block agents,polymers such as polyethylene, polypropylene, polybutadiene, polystyreneand the like can be added or blended with the homopolymers andcopolymers of this invention.

The polymers of the invention can be formed into films and fibers ormolded into shaped objects. It should also be noted that the oxetanerings remain available on the polymeric chain for further crosslinking.Such crosslinking can be accomplished by any suitable means such as byheating the polymeric chain. The novel unsaturated oxetane compounds ofthe invention also find utility as chemical intermediates. It has beenfound that the unsaturated oxetane compounds containing the oxetanemoiety undergo ringopening in the presence of halogens to produce thecorresponding l,4-dihalogeno derivatives as may be represented by thefollowing reaction:

-dihaloketones.

The following examples are included to further illustrate the invention.

EXAMPLE 1 PREPARATION OF 2- ISOPROPYLIDENE-3,3-DIMETHYLOXETANE in apredried l-liter flask is placed 900 ml. of benzene and 27 g. (0.21mole) of potassium tert-butoxide powder. A solution of g. (0.23 mole) of2,2,4- trimethyl-B-oxopentyl tosylate, melting point 40-42 C., in ml. ofbenzene is then introduced into the flask over a 5-minute period. Themixture is heated at reflux for 15 hours under a nitrogen atmosphere,cooled in ice, acidified to pH 6 with acetic acid, and poured intowater. The layers are separated and the aqueous layer is washed withsaturated sodium bicarbonate solution and dried over anhydrous magnesiumsulfate. After filtration and solvent removal, distillation of theresidue gives 25 g. (91 percent) of oxetane, boiling point 91C., 155mm.; ACl-lCl 2980, 1740, and 1,460 cm"; nuclear magnetic resonance(Cl-lcl The invention has been described in considerable detail withparticular reference to certain embodiments thereof, but it will beunderstood that variations and modifications can be effected within thespirit and 15.84 (s), 8.56 (s) and 8.67 (s).'"' 5 scope of the inventionas described hereinbefore. For EXAMPLES 2 21 example, hydrogen andcertain alkyl radicals such as those from three to carbon atoms inlength may be Example 1 is repeated employing the following reac-Subslltuied for the y ethyl groups give tants, solvents, reactiontemperature and time shown in 0115 useful homologs of the novel oxetanecompounds- Table I wherein: 10 We claim:

H l. A compound having the structure: R1(|3C([](1JX RAY 3 R1 0 R4 n 11/u o: :o c 11. R3 R1 11 0 i RPCZK HY wherein R. 5 and Ri eaqhsc tsgi rmth 0 group consisting of rhethylor ethyl.

TABLE I Percent Temp. Time oxetane EX R1 R2 R R4 X R-I Y Solvent 0.)(hr.) product 2 u m 1.. M m 1.. Meth 1-. Meth 1.. Nu OCH; Methanol 68 16as l e y e y y y 0s020m ...d0. Sameasabove 1. Nu 0CHa d0.-.. 68 75-O-CH3 Benzene 78 7 2. 5 OCH3 Methanol 68 65 0 -OC(CH1): Benzene 78 1591 OC(CHs)a d0- 68 15 91 -0c 0H1)3 ...do 78 22 4 H Dimethyl- 78 2 90'formamide H Dimethyl- 170 1.5 so

sulfoxide. OH Methanol 68 5 0 ...do (I) Na H Benzene 78 72 26-O-CCH(CH1)2 ...do... Br Na H do 78 72 68 .d0 Br K OO(CH:1)a .do 78 1a62 .do Cl Na d 7s 15 51 do do. 1 K OC(CH1): do.. 78 15 48 .do... (i Na H1s 15 2e -OCCH(CHa)z do --Sa.me as above K 0C(CHa)1 .do... 78 15 27 ..dofl) Na 0CH3 do...--... 78 15 19 O-CCH(CH:)2

d d Eth 1... Eth 1... Na H do 78 15 1 0 y y -os0cm 21 Ethy1 EthylMethyL. Methyl" Same as above Nu H 78 15 52 EXAMPLE 22 COPOLYMER OFSTYRENE AND 2-ISOPROPYLIDENE-,3-DIMETHYLOXETANE The purpose of thefollowing example is to show that copolymers of2-isopropylidene-3,3-dimethyloxetane and styrene can be made by cationiccatalysts.

In a Pyrex test tube is placed 1.0 g. (8 milli Mole) of2-isopropylidene-3,3-dimethyloxetane, 2.7 g. (0.026 mole) of styrene,and the reaction vessel is purged with nitrogen. Subsequent to coolingthe tube to 75C. in a dry ice-acetone bath a 1.0 g solution of titaniumtetrachloride in 3 ml. of toluene is introduced by syringe. The mixtureis stirred for 6 hours at 75C. and allowed to sit at room temperaturefor 5 days. Methanol is added and a white precipitate formed. Theprecipitate is filtered, reprecipitated and dried to provide 2.7 g. of astyrene-oxetane copolymer. The NMR spectrum indicates 12 mole percent ofoxetane units in copolymer with isopropylidene oxetane incorporated intopolymer.

2. 2-1sopropylidene-3 ,S-dimethyloxetane. 3. A method for thepreparation of a compound having the structure:

m m 11 I 11 (2 wherein R, R, R and R are as defined hereinabove; and Xis selected from the group comprising tosylate,

isobutyroxy, bromine and chlorine, with a base having the structuredimethyloxetane which comprises reacting 2,2,4- trimethyl-3oxopentyltosylate with potassium tertiary butoxide in benzene as a reactionmedium.

7. The method of claim 4 wherein the reaction is conducted at atemperature of about 50 to C.

8. The method for the preparation of the compound of claim 1 whichcomprises reacting 2,2,4-tri-lower alkyl-3-oxopentylisobutyrate with abase selected from the group consisting of alkali metal tertiarybutoxide, alkali metal hydride and sodium methoxide in the presence ofan inert solvent and recovering the compound of claim 1 from theresulting mixture.

9. The method of claim 8 wherein the base is potassium tertiary butoxideand the inert solvent is benzene.

10. A method of producing 3,3-dimethyl-2- isopropenyloxetane whichcomprises reacting 2,2,4- trimethyl-3-oxopentyl isobutyrate withpotassium tertiary butoxide in benzene as a reaction medium.

11. The method of claim 4 wherein the reaction is conducted at atemperature of about 68 to 78C.

ll l I P(%- gg0 UNITED STATES PATENT OFFICE CRCTT Patent No, 3.692.801Dated November 14 1972 Ir1 n ot( )l Alfred G. Robinson, IIT and Ani-hnnyW Mt fn] 111m It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

[ Column 1, lines 10-18, the formula should read:

Column 1, lines 40-47, the formula should read:

H O/CH H2 H2 H CH6 Column 3, line 16, delete "substituted" and insert-polysubstituted-.

Column 3, line 30, delete "Zncl" and insert --ZnCl-.

Column 5, line 51, delete "2Isopropylidene,3-'Dimethyloxetane" andinsert 2Isopropylidene3,3Dimethyloxetane.

Column 5, line 54, delete "catalysts" and insert catalysis--.

Column 6, in the table; in the last heading, after "Percent", insertYield- Signed and sealed this 6th day of March 1973.

L- (SEAL) Attest:

EDWARD M. FLETCHER,JR ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

2. 2-Isopropylidene-3,3-dimethyloxetane.
 3. A method for the preparationof a compound having the structure: wherein R1, R2, R3 and R4 are eachselected from the group consisting of methyl or ethyl, which comprisesreacting a compound having the structure: wherein R1, R2, R3 and R4 areas defined hereinabove; and X is selected from the group comprisingtosylate, isobutyroxy, bromine and chlorine, with a base having thestructure R5Y wherein R5 is selected from the group comprising potassiumand sodium, and Y is a radical selected form the group comprising-OC(CH3)3, -OCH3 and H and recovering said compound from the resultingreaction mixture.
 4. The method of claim 3 wherein the reaction iscarried out in the presence of an inert solvent.
 5. The method of claim4 wherein the base is potassium tertiary butoxide and the inert solventis benzene.
 6. A method of producing2-isopropylidene-3,3-dimethyloxetane which comprises reacting2,2,4-trimethyl-3-oxopentyl tosylate with potassium tertiary butoxide inbenzene as a reaction medium.
 7. The method of claim 4 wherein thereaction is conducted at a temperature of about 50* to 170*C.
 8. Themethod for the preparation of the compound of claim 1 which comprisesreacting 2,2,4-tri-lower alkyl-3-oxopentylisobutyrate with a baseselected from the group consisting of alkali metal tertiary butoxide,alkali metal hydride and sodium methoxide in the presence of an inertsolvent and recovering the compound of claim 1 from the resultingmixture.
 9. The method of claim 8 wherein the base is potassium tertiarybutoxide and the inert solvent is benzene.
 10. A method of producing3,3-dimethyl-2-isopropenyloxetane which comprises reacting2,2,4-trimethyl-3-oxopentyl isobutyrate with potassium tertiary butoxidein benzene as a reaction medium.
 11. The method of claim 4 wherein thereaction is conducted at a temperature of about 68* to 78*C.